Abstract: A method for calibrating an automatic chemical analyzer whereby an improved baseline value is calculated. The analyzer uses a photodetector to detect the amount of light passing through a flow cell and correlates this value to the amount of analyte present in a sample solution. In the preferred embodiment, silica is the analyte under investigation. A baseline solution of a specified (preferably zero) analyte concentration, or a sample solution of unknown analyte concentration, is introduced into a chemical module after chemical reagents have reacted with themselves to form a color complex. The resulting solution is passed to the photodetector which determines the amount of analyte present. This value corresponds to the analyte contaminants within the reagents and can be subtracted out by further calculations.

Abstract: An automatic chemical analyzer includes containers for chemical reagents, a standard (full scale) solution and a baseline solution. An overflow sampler provides a test sample having a chemical concentration to be measured. Computer controlled valve means connect either the baseline solution, standard solution or test sample to an output tube, and a peristaltic pump couples the reagents and the liquid in the output tube to a chemical module where the chemical reaction takes place. The output of the chemical module is coupled to a flow cell in the form of a stream of liquid segments separated by air bubbles. Light at a selected optical frequency is passed directly through the flow cell to a photodetector the output of which is converted to digital form by a computer which stores baseline and full scale values corresponding to the color values of the liquids in the baseline and standard containers.

Abstract: A standard, which is of ceramic material and preferably includes alumina, for spectral reflectance for use in near infrared reflectance measurements of constituents of samples, which constituents comprise oil, moisture and protein. The standard reflects electromagnetic radiation in the wavelength range of 1.0 - 2.5 micrometers and exhibits its best optical characteristics in the operational range of 1.4 - 2.4 micrometers.